Fluoration in the presence of chlorine as a catalyst



A. L. HENNE v FLUORVATION IN THE PRESENCE OF CHLORINE AS A CATALYST Feb'. 12, 1935.

Filed Jan. so, 1931 'Patented Feb. 12, A1935 lUNITED lsrtlss' IPATENT forricr FLUoaA'rroN m- THE PRESENCE or cnLomNs As A cA'rALYs'r Albert L. Henne, Columbus, Ohio, assigner, byv

mesne assignments, to General Motors Corporation, a corporation of Delaware l' Application January 30, 1931, Serial No. 512,4'Zl

s claims. (ci. aso-rc2) tively scarce or rather expensive or, as in the case of antimony pentachloride, it has been necessary to provide a separate process for the manuiacturedshereof.

The objects of my present invention are to provide a catalytic agent which will be relatively cheap and readily available and one which. being usable in either the liquid or the gaseous form, will be easy to meter, and more particularly, to provide a process or processes for manufacturing fiuoro and/or halo-uoro derivatives by causingl a halogen derivative of an aliphatic hydrocarbon to react with ba fluorating agent in the presence of chlorine as the catalytic agent. R

In a specific example relating to the production of dichlorodiuoromethane, the reactants and the reactions are substantially as follows:

accil--zsbra-ciscchrsqeasbch it being understood that the CClzFa is obtained in preference to CClaF and CClFs by suitable con.m

trol of the reaction. y

Ethane derivatives may be reacted upon substantially as` follows;

the principal resulting compound depending upon the -control exercised.

Fig. 1 illustrates diagrammaticallyan appa.v

ratus for carrying out the various steps of my process. In this'type of apparatus a reaction chamber is supplied with antimony trifluoride through the opening 22. -The catalytic. agent chlorine enters the reaction chamber 20 from the tank 38 through the pipe- 39 under the control of the manually or automatically operated valve 40. Carbon tetrachloride is pumped from the tank 36 into the reaction chamber '20 by the pump 21,.shown diagrammatically as kdriven by the motor 21a. The residual antimony trichloride is removed from the reaction chamber 20 through the dump 'valve 22a. The gaseous products (CClaFa, CClsF and unacted uponv CCli) are admitted into the fractionating 4column 23 and the dephlegmator 24=.` The temperature of the decondenser 32 which may be cooled to a degree able pressures and temperatures ln the trac-v phlegmatoris adjusted in accordance with the pressure under which the reaction takes place, so that this combination of pressure and temperature approximates the vapor pressure characteristics of the desired product. The CCL; is 5 converted into CClzFz with a dephlegmator temperature of about 60 F. to 65 F. and a pressure of `about 55 pounds gauge. The rate of reaction is controlled by the steam jacket 23.

The dephlegmator returns to the reaction' 1 Ichamber 20, the partially uorated compound,

such as monouorotrichloromethane, CClsF, and. any unacted upon carbon tetrachloride, and these compounds will be further' uorated to the desired' derivative, CClzFz. The desired pressure in the system is obtained by regulating the rate of dis-e charge of the nished product. This may be done by manual control or by an automatically regulated discharge valve. 32a. y

The washer 25 contains a dilute aqueous solution of caustic soda provided from-the supply chamber 29. The CClzFz is discharged from the dephlegmator into the washers 25 and 26.' The washer 26 is likewise provided with 'a caustic soda solution from the chamber 30. The drier 27 contains aconcentrated solution of sulphuric acid supplied from the chamber 31. Upon leav- .ing the drier 27, the CClzFz passes through the necessary to liquefy the gas which is then discharged from the condenser and Acollected in the iiask or tank 33. A relief diaphragm and a pres= 4sure gauge 35 are provided.

While l have described a. method oi manufacturing dichlorodiluoromethane, it is possible to obtain other derivatives of methane, for example, CHzClF, CI-IClzF, CHClFz, ,C ClzFz, CClFa.- and. CClaF, it being understood that by the process outlined above the substances fluorated in the reaction chamber 20` contain a number cf chlorine atoms equal to the required sum of the chlorine and urine atoms in the nal product.` The pressures and the temperatures 'in .the fractionating column and the dephlegmator Aapproximate the vapor pressure characteristics of the desired product. A

It is possible by my process, using chlorine as the catalytic agent, to obtain halo-nuoro derivatives of other hydrocarbons than methane. Thus, a chlorine derivative of ethane, propane or butane, etc.'may be introduced into the reaction chamber 20, together with` the iiuoratingagent SbF-s' and the catalytic agent, chlorine, and by subjecting gaseous reaction products to the suitdesired halo-nuoro derivative of any of the above hydrocarbons may be obtained. Such products are CzChFz, CsHzClsFz, and C4H4C12F4.

While I have described specic apparatus and specific steps in a process for purposes of illustration, it is understood that broadly my invention is the fiuoration of halo-derivatives of aliphatic hydrocarbons in the presence of chlorine as a catalyst.

What is claimed is as follows:

1. The method of manufacturing ahalo-iluoro derivative of an aliphatic hydrocarbon from a halogenated aliphatic hydrocarbon containing halogen other than iluorine which consists in contacting the hydrocarbon derivative with SbF'3 in the presence of chlorine as a catalytic agent, replacing at least a halogen atom other than uorine of the hydrocarbon with fiuorine, controlling the pressure and temperature conditions to drive off the desired substituting product before further fluorine substitutions have been made and returning to the reaction field insuiciently fluor-ated compounds.

tionating column 23 and a dephlegmator 24, the

2. The method of manufacturing a halo-iluoro derivative of methane which consists in contacting a halogen derivative of methane containing halogen other than iluorine with SbFa in the presence of chlorine as a catalyst.

3. The method of manufacturing a halo-nuoro derivative of ethane which consists in contacting a halogen derivative of ethane containing halogen other than uorine with SbFs in the presence of chlorine as a catalyst.

4. The method of manufacturing dichlorodifluoro methane which consists in contacting CCl4 with SbFs in the presence of chlorine as a catalyst.

5. The process comprising interacting a halogenated aliphatic hydrocarbon containing at least one halogen atom other than uorine with SbF: in the presence of chlorine as a catalytic agent.

6. In the process of fluorating a halogenated aliphatic hydrocarbon containing halogen other than fluorine, the st'ep of adding free chlorine to the reaction zone. y

ALBERT L. HENNE. 

